/*******************************************************************************
 * Copyright (c) 2005, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - Initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.browser;

import java.io.File;

import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.FileTransfer;
import org.eclipse.swt.dnd.TransferData;
/**
 *
 */
public class WebBrowserViewDropAdapter extends DropTargetAdapter {
   /**
    * The view to which this drop support has been added.
    */
   private BrowserViewer view;

   /**
    * The current operation.
    */
   private int currentOperation = DND.DROP_NONE;

   /**
    * The last valid operation.
    */
   private int lastValidOperation = DND.DROP_NONE;
   
   protected WebBrowserViewDropAdapter(BrowserViewer view) {
		this.view = view;
	}

   /* (non-Javadoc)
    * Method declared on DropTargetAdapter.
    * The mouse has moved over the drop target.  If the
    * target item has changed, notify the action and check
    * that it is still enabled.
    */
   private void doDropValidation(DropTargetEvent event) {
       //update last valid operation
       if (event.detail != DND.DROP_NONE)
           lastValidOperation = event.detail;
       
       //valid drop and set event detail accordingly
       if (validateDrop(event.detail, event.currentDataType))
           currentOperation = lastValidOperation;
       else
           currentOperation = DND.DROP_NONE;
       
       event.detail = currentOperation;
   }

   /* (non-Javadoc)
    * Method declared on DropTargetAdapter.
    * The drop operation has changed, see if the action
    * should still be enabled.
    */
   public void dragOperationChanged(DropTargetEvent event) {
       doDropValidation(event);
   }

   /* (non-Javadoc)
    * Method declared on DropTargetAdapter.
    * The mouse has moved over the drop target.  If the
    * target item has changed, notify the action and check
    * that it is still enabled.
    */
   public void dragOver(DropTargetEvent event) {
       //set the location feedback
   	 event.feedback = DND.FEEDBACK_SELECT;

       //see if anything has really changed before doing validation.
       doDropValidation(event);
   }

   /* (non-Javadoc)
    * Method declared on DropTargetAdapter.
    * The user has dropped something on the desktop viewer.
    */
   public void drop(DropTargetEvent event) {
       //perform the drop behaviour
       if (!performDrop(event.data))
           event.detail = DND.DROP_NONE;
       
       currentOperation = event.detail;
   }

   /* (non-Javadoc)
    * Method declared on DropTargetAdapter.
    * Last chance for the action to disable itself
    */
   public void dropAccept(DropTargetEvent event) {
       if (!validateDrop(event.detail, event.currentDataType))
           event.detail = DND.DROP_NONE;
   }

	public void dragEnter(DropTargetEvent event) {
		if (event.detail == DND.DROP_DEFAULT)
			event.detail = DND.DROP_COPY;

       doDropValidation(event);
	}

	/**
    * Performs any work associated with the drop.
    * <p>
    * Subclasses must implement this method to provide drop behavior.
    * </p>
    *
    * @param data the drop data
    * @return <code>true</code> if the drop was successful, and 
    *   <code>false</code> otherwise
    */
	protected boolean performDrop(Object data) {
		if (data instanceof String[]) {
			String[] s = (String[]) data;
			if (s == null || s.length == 0)
				return true;
			File f = new File(s[0]);
			try {
				view.setURL(f.toURL().toExternalForm());
			} catch (Exception e) {
				// TODO
			}
		}
		
		return true;
	}

	/**
    * Validates dropping on the given object. This method is called whenever some 
    * aspect of the drop operation changes.
    * <p>
    * Subclasses must implement this method to define which drops make sense.
    * </p>
    * 
    * @param target the object that the mouse is currently hovering over, or
    *   <code>null</code> if the mouse is hovering over empty space
    * @param operation the current drag operation (copy, move, etc.)
    * @param transferType the current transfer type
    * @return <code>true</code> if the drop is valid, and <code>false</code>
    *   otherwise
    */
	protected boolean validateDrop(int operation, TransferData transferType) {
		if (FileTransfer.getInstance().isSupportedType(transferType))
			return true;
		/*if (ResourceTransfer.getInstance().isSupportedType(transferType))
			return true;
		if (LocalSelectionTransfer.getInstance().isSupportedType(transferType))
			return true;*/
		
		return false;
	}
}